Loss And Loss Adjustment Expense Reserves (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2019	Sep. 30, 2019	Sep. 30, 2018
Unusual or Infrequent Item, or Both [Line Items]
Prior year claims and claims adjustment expense		$ 10,323	$ 70,398
Adjustments for prior year claims		715,451	695,678
Catastrophe [Member]
Unusual or Infrequent Item, or Both [Line Items]
Loss from catastrophes, net of reinsurance benefits		17,000	24,000
Loss from catastrophes		20,000	34,000
Adjustments for prior year claims		$ 3,000
Fire [Member]
Unusual or Infrequent Item, or Both [Line Items]
Loss from catastrophes, net of reinsurance benefits	$ 40,000		10,000
Loss from catastrophes	208,000		$ 21,000
Benefit from sale of subrogation rights	$ 10,000